/**
 * https://leetcode.com/problems/number-of-boomerangs/description/
 * Difficulty:Easy
 *
 * Given n points in the plane that are all pairwise distinct,
 * a "boomerang" is a tuple of points (i, j, k) such that the distance
 * between i and j equals the distance between i and k (the order of the tuple matters).
 *
 * Find the number of boomerangs.
 * You may assume that n will be at most 500 and
 * coordinates of points are all in the range [-10000, 10000] (inclusive).
 *
 *
 *
 * Example:
 * Input:
 * [[0,0],[1,0],[2,0]]
 * Output:
 * 2
 * Explanation:
 * The two boomerangs are [[1,0],[0,0],[2,0]] and [[1,0],[2,0],[0,0]]
 *
 *
 *
 * 解释
 *
 * 给定一个Point的数组, 找到所有的长度为3的Point数组(i, j, k)
 * 使得 i&j, i&k 的距离相同
 * 顺序有关
 *
 */

/**
 * @param {number[][]} points
 * @return {number}
 */
var numberOfBoomerangs = function (points) {
    if (points.length < 3) return 0;
    var ret = 0;
    for (var i = 0; i < points.length; i++) {
        var p1 = points[i];
        var disMap = {};

        for (var j = 0; j < points.length; j++) {
            if (i == j) continue;
            var p2 = points[j];
            var dis = getDis(p1, p2);
            if (disMap[dis] == undefined) disMap[dis] = 1;
            else disMap[dis] += 1;
        }

        for (var key in disMap) {
            var n = disMap[key];
            ret += n * (n - 1)
        }

    }

    return ret;

};

function getDis(p1, p2) {
    var d1 = p2[1] - p1[1];
    var d2 = p2[0] - p1[0];
    return d1 * d1 + d2 * d2;
}

console.log(numberOfBoomerangs([[0, 0], [1, 0], [2, 0]]) == 2);
console.log(numberOfBoomerangs([[1, 1]]) == 0);
console.log(numberOfBoomerangs([[1, 1], [1, 2]]) == 0);
console.log(numberOfBoomerangs([[0, 0], [1, 0], [-1, 0], [0, 1], [0, -1]]) == 20);
console.log(1062 == numberOfBoomerangs([[693, 334], [439, 334], [421, 159], [985, 957], [354, 761], [762, 972], [541, 716], [852, 850], [662, 482], [399, 217], [154, 173], [15, 506], [851, 364], [790, 263], [491, 172], [37, 537], [859, 828], [871, 280], [987, 856], [590, 341], [970, 352], [665, 511], [69, 517], [361, 83], [351, 112], [300, 506], [638, 667], [364, 489], [32, 154], [104, 875], [679, 141], [412, 538], [969, 636], [170, 956], [844, 760], [649, 814], [465, 314], [326, 886], [183, 39], [969, 535], [152, 621], [393, 790], [289, 109], [631, 673], [264, 735], [548, 295], [877, 313], [833, 198], [949, 355], [155, 793], [468, 156], [960, 933], [823, 286], [171, 358], [677, 140], [245, 181], [761, 990], [323, 50], [100, 954], [75, 364], [42, 624], [659, 919], [289, 844], [469, 238], [551, 976], [383, 19], [133, 343], [304, 956], [981, 475], [666, 11], [967, 912], [192, 729], [902, 868], [131, 2], [174, 207], [718, 216], [183, 377], [487, 472], [573, 957], [62, 125], [933, 797], [496, 418], [141, 153], [726, 474], [980, 393], [485, 948], [305, 30], [29, 559], [898, 160], [562, 424], [719, 280], [641, 902], [10, 480], [726, 583], [789, 140], [708, 723], [938, 557], [493, 431], [710, 220], [905, 690], [613, 391], [638, 270], [421, 667], [829, 671], [180, 743], [95, 899], [24, 88], [154, 386], [569, 232], [969, 710], [373, 30], [433, 663], [587, 279], [94, 649], [499, 351], [339, 464], [742, 330], [86, 515], [349, 915], [186, 881], [11, 634], [133, 387], [722, 287], [773, 643], [519, 742], [354, 244], [124, 139], [259, 63], [418, 353], [712, 269], [705, 404], [733, 799], [734, 819], [315, 435], [87, 853], [669, 450], [487, 802], [837, 562], [89, 610], [205, 960], [704, 911], [557, 829], [403, 816], [892, 821], [522, 605], [443, 579], [361, 528], [378, 447], [700, 45], [882, 787], [899, 551], [589, 386], [353, 426], [948, 794], [36, 506], [107, 92], [417, 664], [921, 820], [480, 166], [994, 354], [123, 437], [933, 484], [317, 312], [931, 17], [709, 165], [156, 608], [69, 745], [995, 422], [171, 295], [569, 559], [801, 676], [652, 571], [340, 925], [743, 172], [91, 89], [527, 566], [878, 812], [50, 196], [124, 333], [213, 186], [499, 370], [794, 568], [115, 141], [342, 639], [437, 263], [198, 590], [939, 202], [513, 631], [128, 257], [804, 571], [346, 683], [138, 225], [495, 540], [421, 972], [226, 634], [158, 725], [356, 952], [645, 472], [446, 339], [111, 883], [603, 661], [825, 542], [216, 339], [174, 344], [596, 330], [267, 294], [13, 757], [519, 860], [650, 292], [832, 876], [279, 990], [953, 635], [295, 598], [107, 741], [937, 570], [976, 540], [584, 801], [83, 800], [492, 609], [496, 440], [939, 763], [735, 304], [873, 606], [164, 523], [251, 349], [751, 530], [339, 704], [165, 986], [302, 625], [79, 591], [547, 407], [484, 131], [561, 919], [931, 53], [528, 427], [494, 819], [543, 581], [123, 768], [187, 639], [643, 438], [988, 394], [320, 680], [98, 486], [18, 752], [463, 98], [695, 10], [505, 179], [142, 66], [98, 425], [472, 978], [853, 966], [797, 748], [547, 272], [516, 86], [912, 159], [877, 900], [553, 197], [932, 3], [35, 951], [107, 498], [49, 154], [861, 906], [334, 3], [325, 784], [428, 797], [763, 633], [115, 560], [381, 14], [185, 897], [100, 97], [408, 329], [349, 313], [879, 634], [316, 914], [585, 775], [765, 986], [930, 626], [892, 616], [629, 569], [752, 409], [366, 515], [395, 833], [428, 776], [847, 613], [26, 300], [62, 786], [629, 763], [100, 508], [397, 416], [775, 982], [544, 540], [320, 826], [518, 565], [794, 499], [134, 546], [908, 853], [62, 303], [686, 842], [432, 534], [807, 810], [834, 869], [596, 815], [984, 696], [324, 382], [465, 451], [716, 361], [343, 37], [187, 861], [602, 981], [360, 88], [879, 620], [941, 293], [924, 628], [135, 708], [162, 942], [870, 996], [163, 466], [811, 500], [515, 487], [234, 332], [290, 950], [693, 633], [339, 880], [494, 293], [213, 854], [382, 444], [475, 323], [738, 751], [951, 873], [811, 465], [168, 681], [813, 683], [499, 977], [535, 14], [464, 769], [346, 107], [72, 391], [740, 411],
        [623, 587], [57, 836], [793, 439], [281, 620], [114, 371], [371, 418], [596, 534], [883, 764], [567, 697], [800, 67], [674, 335], [433, 490], [457, 132], [949, 529], [523, 690], [292, 147], [629, 349], [335, 422], [140, 968], [43, 255], [339, 766], [25, 936], [653, 260], [52, 220], [957, 204], [287, 983], [540, 721], [826, 997], [205, 127], [878, 728], [169, 170], [227, 798], [520, 563], [221, 660], [883, 616], [267, 223], [382, 292], [511, 35], [553, 563], [608, 862], [768, 895], [198, 660], [968, 376], [9, 173], [503, 887], [254, 673], [57, 481], [823, 929], [396, 44], [942, 280], [12, 209], [855, 747], [854, 366], [134, 759], [281, 742], [973, 401], [638, 171], [413, 958], [899, 422], [484, 755], [661, 90], [780, 71], [923, 603], [0, 320], [0, 942], [952, 12], [504, 807], [759, 358], [525, 894], [117, 158], [636, 90], [560, 626], [614, 973], [937, 865], [748, 421], [620, 409], [863, 400], [832, 786], [4, 833], [458, 356], [127, 410], [368, 631], [569, 128], [341, 446], [374, 458], [605, 10], [901, 165], [989, 867], [490, 926], [732, 238], [699, 705], [0, 562], [457, 832], [348, 461], [17, 807], [169, 497], [569, 538], [128, 139], [18, 470], [585, 392], [280, 542], [754, 533], [707, 743], [400, 550], [21, 485], [788, 720], [190, 140], [634, 647], [325, 983], [461, 694], [142, 630], [191, 63], [520, 320], [554, 538], [142, 492], [930, 422], [34, 685], [308, 94], [780, 708], [644, 802], [545, 784], [522, 87], [925, 157], [735, 602], [492, 548], [296, 986], [530, 840], [49, 51], [512, 956], [589, 654], [448, 872], [428, 482], [557, 88], [576, 337], [797, 220], [139, 694], [5, 14], [782, 282], [523, 869], [236, 15], [417, 884], [353, 299], [724, 754], [350, 236], [710, 292], [242, 158], [164, 23], [641, 721], [111, 569], [410, 260], [790, 902], [955, 147], [916, 89], [781, 439], [958, 17], [806, 375], [901, 511], [674, 978], [265, 377], [566, 976], [669, 161], [134, 833]]))